Magnetic holding unit



1966 K. H. GRANZOW MAGNETIC HOLDING UNIT Filed Dec. 17, 1964 United States Patent 3,294,433 MAGNETEC HQLBHNG UNIT Kurt H. Granzow, fiterling, lili, assignor to Lawrence rothers, line, Sterling, fill, a corporation of illinois Filed Dec. 17, 1%4, Ser. No. 418,977 3 Claims. (tCl. 29225l.5)

This invention relates generally to magnetic holding units and more particularly to the means employed for retaining a magnet assembly or the like in such a unit.

Various means for retaining a magnet assembly in the housing of a magnetic holding unit have been resorted to in the past; and in order to give the magnet assembly a certain freedom of movement, whereby to accommodate the ange displayed by an approaching strike plate or armature, such schemes as central pivot posts and ears or flanges struck from the walls of the housing have been utilized. However, the pivot post construction requires an additional part, the post itself, as well as a number of separate perforating operations, namely on the housing and on each of the components of the magnet assembly. On the other hand, while the struck element arrangement avoids the need for a pivot post, a number of flanging or punching operations are required in forming the housing to secure the magnet assembly. These retention schemes have added substantially to the cost of the prior art magnetic holding units.

Therefore, an important object of the present invention is to provide a magnetic holding unit that is comprised of a minimum number of parts and that can be assembled in a minimum number of operations.

Another object of the invention is to provide a low cost magnetic holding unit.

A more general object of the invention is to provide a new and improved magnetic holding unit.

A further object of the invention is to provide a magnetic holding unit which combines freedom of magnet movement with security in mounting the magnet in its housing.

These and other objects and features of the invention will become apparent from a consideration of the following descriptions.

A devicein accord with the invention includes a onepiece housing of non-magnetic material which housing is arranged to define a generally rectangular cavity for receiving magnet means therein, confronting walls of the cavity having vertical front and back edges thereof shaped to define horizontally extending, vertically spaced shoulders. Magnet means are situated in the cavity of the housing, and these magnet means include a main body portion that is spaced generally inwardly from the walls of the cavity to be shiftably disposed therein, the magnet means further having abbreviated arms that extend beyond the confronting walls of the housing to reside between the spaced shoulders thereof. These arms cooperate with the shoulders in retaining the magnet means shiftably within the housing.

In order that the principle of the invention may be readily understood, a single embodiment thereof, but to which the application is not to be restricted, is shown in the accompanying drawing wherein:

FIG. 1 is a perspective view of a magnetic holding unit constructed in compliance with the invention and shown mounted on a door frame member for securing a door that is provided with a magnetically permeable armature plate;

FIG. 2 is an enlarged, top plan view of the catch installation of FIG. 1;

FIG. 3 is a view taken substantially along the section line 3-3 of FIG. 2 and showing both the loose mounting of the magnet assembly within the housing and the abbreviated arms which extend from. the magnet assembly beyond the confronting Walls of the housing for use in mounting the magnet assembly in the housing;

FIG. 4 is a side elevational view taken substantially along the line 44 of FIG. 3, a portion of the housing being broken away to reveal details of the magnet assembly and its cooperation with the housing;

PEG. 5 is a perspective View of the housing with the magnet assembly removed; and

REG. 6 is an exploded perspective View of the components of the magnet assembly.

Referring now in detail to the drawing, specifically to F165. 1 and 2, a magnetic holding unit indicated gen erally by the numeral W is seen to be mounted on a door frame member 12 in position to secure a door 14 in closed position by magnetically attracting a permeable armature or strike plate 16. As is best shown in FIG. 2, the armature plate 16 is perforated with a central aperture 18 for passing a screw 2t or other fastener into aggressive engagement with the material of door 14. Advantageously, the aperture 18 is fashioned with a conical counterbore to receive the head of a fiat-headed screw in flush relationship. When a single fastener is employed in mounting the armature plate to the door, it is desirable to extrude one or more lugs 22- tfrom the rear of the armature plate for engaging the face of door 14 in a piercing manner. Provision of one or more lugs 22 prevents the armature plate from rotating about the fastening screw 24}.

The magnetic holding unit tilt includes a housing 24 and a magnet arrangement The housing 24 is fabricated from a non-magnetic material such as sheet aluminum, and the magnet arrangement 26 takes as its components a permanent magnet 28 and a. pair of magnetically permeable pole plates 3b? and 32. The magnet 23 is selected to be of the bar type, and the pole plates 30' and 32 are coupled to the magnet 28 at opposite pole faces thereof.

Referring to FIG. 5, the housing 24 is seen to be of strap type construction including mounting flanges 34 and 36 and an upwardly deflected mid-portion or body 38. The mounting flanges 34 and as are fashioned with individual elongated slots 40 for passing the shanks of screws 42 or other fasteners into a frame member as is illustrated in FIG. 1. Returning to FIG. 5, the upwardly deflected mid-portion 38 of the housing defines a generally rectangular cavity for receiving the magnet arrangement 26. Specifically, the mid-portion 38 of the strap-type housing 24 includes a ceiling plate 44 and confronting sidewalls 46 and 48. In compliance with an important feature of the invention, the front and back edges of the confronting sidewalls 46 and 43 are notched out to define horizantially extend-ing, upper front and back shoulders 56 and horizontally extending, lower front and back shoulders 52. The upper and lower shoulders 50 and 52 are arranged in vertically spaced, front and back pairs having clear spaces between the vertically confronting shoulders. So arranged, the upper and lower shoulders 50 and 52 define abutment means for use in shiftably retaining the magnet arrangement 26 in the housing 24.

With reference to FIG. 3, the main body portion of the magnet arrangement 26 is seen to be received in the cavity defined by the mid-portion 38 of housing 24 spaced generally inwardly from the sidewalls 4e and 48 thereof. Thus, the magnet arrangement 26 is susceptible to moderate lateral shifting within the housing 24. This main body portion of the magnet arrangement is also spaced generally inwardly from the ceiling 44 and the underlying structural member which is en aged by the flanges 34 and 36 of the housing. Thus, moderate vertical shifting of the magnet arrangement within the housing is also permitted.

Turning to FIG. 6 for a description of the components of the magnet arrangement 26, the pole plates 30 and 32 are seen to be fashioned with spaced bosses or protrusions 54 which are situated at eccentric locations to engage coupling apertures 56 formed in the magnet 28. The relative diameters of the bosses S4 and the apertures 56 is selected to provide an interference fit therebetween and thereby a firm mechanical connection between the pole plates and the magnet. The bosses 54 comprise detents which are extruded from the pole plates for this purpose. The pole plates 30 and 32 are advantageously fabricated to be imperforate elements, and it is recognized that the magnet 28 need not be bored completely through in developing the apertures 56, although drilling through the magnet is a convenient way of forming apertures on opposite faces of the magnet for receiving the bosses of both pole plates.

The magnet 28 is desirably fabricated from magnetic particles, as for example ferrites, bonded together with a rubber composition as by being molded therein; and a bar magnet of this construction is easily provided with the apertures 56 and display admirable resistance to fracture or cracking during assembly and use. The pole plates 30 and 32, on the other hand, are advantageously fabricated from a suitable magnetic material such as mild steel; and in compliance with another important feature of the invention, the pole plates 30 and 32 are arranged to be generally I-shaped, comprising a generally rectangular body 58 with abbreviated arms 60 extending therefrom in parallel relationship. The abbreviated arms 60 are selected to take such a length that they extend beyond the confronting sidewalls 46 and 48 of the housing 24- when the magnet arrangement 26 is received therein, as is well illustrated in FIG. 3. Furthermore, the arms 60 are intended to reside shiftably between the spaced upper and lower shoulders 50 and 52, as is shown in FIG. 4, in order to cooperate therewith for retaining the magnet arrangement shiftably within the housing 24. From an observation of FIG. 4, it will be apparent that the overall height of the magnet arrangement 26 is less than the vertical dimension between the upper and lower shoulders 50 and 52. cooperatively, the clear spaces between the abbreviated arms 60' that extend from a common end of either one of the pole plates is greater that the corresponding horizontal dimension of the cooperating sidewall 46 or 48 of the housing. Thus, the magnet arrangement may shift vertically, horizontally, an angularly within the housing in order to accommodate the angle displayed by the approaching armature plate 16 upon closing the door 14. In addition, the shoulders 50 and 52 and the arms 60 are selected to be of such a length as to retain the magnet arrangement 26 positively within the housing 24.

From the foregoing descriptions, it will be apparent that the magnetic holding unit of the invention comprises but four components, namely a one-piece housing and a magnet assembly including a bar magnet and two permeable pole plates. In addition to being fabricated from a minimum number of parts, the instant magnetic holding unit is easily assembled. For example, the components of the magnet arrangement are easily made by simple stamping operations, and the magnet arrangement itself is easily handled as a single part once it has been assembled because the pole plates are both mechanically and magnetically coupled to the bar magnet. Accordingly, once the strap type housing has been stamped from fiat stock, it may be easily bent around the magnetic arrangement to complete the assembly in a single step. The freedom of movement and security of assembly of the resultant structure has been described hereinabove; and it has been found that a properly dimensioned magnetic holding unit constructed in compliance with the invention is highly resistant to disassembly in handling or use. Either the housing must be radically deformed or the abbreviated arms must be broken in order to effect separation of the basic components.

The specific example herein shown and described is to be considered as being primarily illustrative. Various changes in structure will, no doubt, occur to those skilled in the art; and such changes are to be understood as forming a part of this invention insofar as they fall within the spirit and scope of the appended claims.

The invention is claimed as follows:

1. A magnetic holding unit comprising: a housing of non-magnetic material, including a ceiling means and sidewall elements extending from said ceiling means to define therewith a generally rectangular cavity for receiving magnet means therein, said ceiling means having surface means acting as abutment means to arrest movement of the magnet means in one direction and said sidewall elements having respectively forwardly .and rearwardly disposed shoulders extending from the front and back edges of said elements generally parallel to and confronting said ceiling means spaced apart therefrom to act as abutment means for arresting movement of said magnet means in the opposite direction; a magnet means in said cavity having a main body portion dimensioned to reside loosely in said cavity generally spaced apart from said sidewall elements for shiftable movement relative to said housing, said magnet means having a first plurality of abbreviated arms disposed generally forwardly of said front edges between said ceiling means and said forwardly disposed shoulders and laterally beyond said sidewall elements to abut said front edges for arresting movement of said magnet means in one transverse direction and said magnet means further having a second plurality of abbreviated arms disposed generally rearwardly of said back edges between said ceiling means and said rearwardly disposed shoulders and laterally beyond said sidewall elements to abut said back edges for arresting movement of said magnet means in the opposite transverse direction, said first arms being spaced from said second arms by a distance greater than the span between said front and back edges, whereby saidarms, said edges, said shoulders and said ceiling means coact to retain said magnet means shiftably in said housing.

2. A magnetic holding unit according to claim 1 wherein said magnet means includes .a magnet and a pair of pole plates coupled to said magnet and wherein said abbreviated arms are parts of said pole plates.

3. A magnetic holding unit according to claim 1 wherein the span between said front edges and the span between said back edges are open to expose said magnet means for coaction with an armature plate.

References Cited by the Examiner UNITED STATES PATENTS 2,132,967 10/1938 Pennell 339272 2,532,068 11/1950 Larsen 339-272 2,888,291 5/1959 Scott et al. 292-2515 3,100,663 8/1963 Loeb 292251.5 3,149,868 9/1964 Louis 292--251.5 3,155,409 11/1964 Schlissel 292251.5

EDWARD C. ALLEN, Primary Examiner.

RICHARD E. MOORE, Examiner. 

1. A MAGNETIC HOLDING UNIT COMPRISNG: A HOUSING OF NON-MAGNETIC MATERIAL, INCLUDING A CEILING MEANS AND SIDEWALL ELEMENTS EXTENDING FROM SAID CEILING MEANS TO DEFINE THEREWITH A GENERALLY RECTANGULAR CAVITY FOR RECEIVING MAGNET MEANS THEREIN, SAID CEILING MEANS HAVING SURFACE MEANS ACTING AS ABUTMENT MEANS TO ARREST MOVEMENT OF THE MAGNET MEANS IN ONE DIRECTION AND SAID SIDEWALL ELEMENTS HAVING RESPECTIVELY FORWARDLY AND REARWARDLY DISPOSED SHOULDERS EXTENDING FROM THE FRONT AND BACK EDGES OF SAID ELEMENTS GENERALLY PARALLEL TO AND CONFRONTING SAID CEILING MEANS SPACED APART THEREFROM TO ACT AS ABUTMENT MEANS FOR ARRESTING MOVEMENT OF SAID MAGNET MEANS IN THE OPPOSITE DIRECTION; A MAGNET MEANS IN SAID CAVITY HAVING A MAIN BODY PORTION DIMENSIONED TO RESIDE LOOSELY IN SAID CAVITY GENERALLY SPACED APART FROM SAID SIDEWALL ELEMENTS FOR SHIFTABLE MOVEMENT RELATIVE TO SAID HOUSING, SAID MAGNET MEANS HAVING A FIRST PLURALTY OF ABBREVIATED ARMS DISPOSED GENERALLY FORWARDLY OF SAID FRONT EDGES BETWEEN SAID CEILING MEANS AND SAID FORWARDLY DISPOSED SHOULDERS AND LATERALLY BEYOND SAID SIDEWALL ELEMENTS TO ABUT SAID FRONT EDGES FOR ARRESTING MOVEMENT OF SAID MAGNET MEANS IN ONE TRANSVERSE DIRECTION AND SAID MAGNET MEANS FURTHER HAVING A SECOND PLURALITY OF ABBREVIATED ARMS DISPOSED GENERALLY REARWARDLY OF SAID BACK EDGES BETWEEN SAID CEILING MEANS AND SAID REARWARDLY DISPOSED SHOULDERS AND LATERALLY BEYOND SAID SIDEWALL ELEMENTS TO ABUT SAID BACK EDGES FOR ARRESTING MOVEMENT OF SAID MAGNET MEANS IN THE OPPOSITE TRANSVERSE DIRECTION, SAID FIRST ARMS BEING SPACED FROM SAID SECOND ARMS BY A DISTANCE GREATER THAN THE SPAN BETWEEN SAID FRONT AND BACK EDGES, WHEREBY SAID ARMS, SAID EDGES, SAID SHOULDERS AND SAID CEILING MEANS COACT TO RETAIN SAID MAGNET MEANS SHIFTABLY IN SAID HOUSING. 